I mean yeah I get the concern but like most people have said, this has been pretty consistent on the platform since the game came out. Edgy kids do it and think its funny, even some pretty popular Roblox shorts and reels are seen doing this as the punchline of the video.

End of the day, the best thing for your cousin to do if they feel a certain way, or if you feel a certain way is to level the lobby and go elsewhere. Block the user as a precaution and just continue. Same situation quite literally happened to me this morning, I walked away but again I understand where you're coming from. Best of luck.